chemistry transition metals

http://filestore.aqa.org.uk/subjects/AQA-CHEM5-QP-JAN12.PDF

could somone pls help me understand the equation in q8 part ii about the complex standing in air ????? thanks !!!

Have you looked at the mark scheme? What don't you understand?

yeah the mark scheme gives this 4(NH2CH2CH2NH2)3 (2+) + O2 + 2H2O GIVES 4(NH2CH2H2NH2)3 (3+) + 4OH-

I just dont understand how you go about constructing the equation ?

You've missed the cobalt off but no matter.

Write a half equation for cobalt oxidation from 2 to 3

Write a half equation for oxiygen reduction to hydroxide.

Balance electrons and combine half equations.

The ligands on the cobalt do not change.

You've missed the cobalt off but no matter.

Write a half equation for cobalt oxidation from 2 to 3

Write a half equation for oxiygen reduction to hydroxide.

Balance electrons and combine half equations.

The ligands on the cobalt do not change.

This is how far I get , not sure where I went wrong ? And how do you know that oxygen is reduced to hydroxide ?